Posterior shoulder dislocations are rare and account for less than 4% of all shoulder dislocations, with only 6.6% of these proving to be bilateral. More importantly, the majority of posterior shoulder dislocations continue to represent a diagnostic trap for the unwary physician who first sees patients with this condition. This report describes the treatment of a locked bilateral posterior dislocation of the shoulder with an associated impression fracture of both articular surfaces of the humeral heads due to an epileptic seizure. The osteochondral autograft obtained from the left humeral head was sutured to the dominant (right) side and the hemiarthroplasty was performed on the contralateral non-dominant shoulder. Posterior bilateral dislocation of the shoulder is still a diagnostic challenge. In the chronic setting, bilateral hemiarthroplasty should be postponed as long as possible since posterior bilateral dislocation is usually experienced by middle-aged active males.